1. Field of the Invention
The present invention relates to a frame rate converting apparatus for converting various kinds of frame rates of image signals which are generated with the frame rates, and outputting image signals in conformity with an output frame rate, and also relates to an imaging apparatus using the frame rate converting apparatus.
Priority is claimed on Japanese Patent Application No. 2005-285182, filed Sep. 29, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
In conventional TV or movie video production, the frame rate, that is, the number of imaged frames per second, is varied in imaging so as to apply special effects to images. For example, when the frame rate of an image signal (obtained by imaging) is higher than that assigned for a reproduced signal, slow-speed reproduced images are obtained when the images are reproduced at the frame rate assigned for the reproduced signal. On the other hand, when the frame rate of an image signal is lower than that assigned for a reproduced signal, high-speed reproduced images are obtained when the images are reproduced at the frame rate assigned for the reproduced signal. The speed of such slow-speed or high-speed reproduced images depends on a variation from the frame rate of the image signal to the frame rate of the reproduced signal, and can be controlled by varying the frame rate of the image signal or the reproduced signal.
In recent years, in imaging using the technique as described above, an electronic imaging apparatus for varying the frame rate of the image signal has been popularly used. Generally, an electronic viewfinder or a monitor is connected to the electronic imaging apparatus, and the operator performs imaging while checking an image shown in the viewfinder or the monitor. However, when the frame rate of the image signal is varied while imaging, if the frame rate of the image shown in the viewfinder or the monitor is also varied, the operator cannot appropriately check the conditions necessary for imaging (e.g., an angle of view or focusing), based on the shown image. In consideration of this, a method for converting various kinds of frame rates of image signals to a desired frame rate has been suggested.
For example, in an imaging apparatus disclosed in Reference Document 1 (Japanese Unexamined Patent Application, First Publication No. 2005-039712), when the frame rate of the image signal is converted to a lower frame rate, a process of adding frames together is performed, while when the frame rate of the image signal is converted to a higher frame rate, the same frame is repeatedly used. An imaging apparatus disclosed in Reference Document 2 (Japanese Unexamined Patent Application, First Publication No. 2005-057808) has a frame rate converting section for computing a ratio between frame rates before and after conversion, and reproducing the image signal based on the computed ratio.